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- Patented .lune 10, 1924;

UNITED STATES v 1,497,137 PATENT OFFICE.

EDWARD S. FARBOW, JR, OFROCBESTER; NEW You, ASSIGNOB TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

DE'JOLOBIZING CELLULOSIC MATERIAL SUCH AS FILM BASE.

Ho Drawing.

To all whom it may concern Be it known that I, EDWARD S. FARROW Jr., a citizen of the United States of America, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Dccolorizing Cellulosic Material Such as Film Base, of which the following is a full, clear, and exactspecification.

This invention relates to a process for removing d ye from tinted or colored material. such for example as film base or support. one object of the invention is to provide a. process for removing dye from such material inexpensively, rapidly and with a minimum number of-operations. Other objects will hereinafter appear.

My invention is especially useful when employed in the removal of d 'e from tinted ccllulosic bases of photograp ic fi l-ms. One embodiment of it will. therefore, be described in connection with such film by way of example; but the invention is, of course, not limited to this particular illustrative field. Photographic have come into extensive use, the bases or supports of which contain a colored or dyed layer. The latter "may be upon either side of the main su port. or many be located throughout t e entire cellulosic material.

'When scrap or other waste pieces of such colored film base accumulate it is desirable to eclaim them by removing the color andusn; the ceflulosic addition compounds again. I have discovered that this can be done rapidly, inexpensively and with a minimum of work by dissolving the colored scrap and passing the solution through decolorizing carbon, such as hone-char.

My invention can be employed in the lecolorizing of film bases,whether the latter contain. cellulose nitrate. cellulose acetate or cellulose ethers, these bein typical illustrations of the cellulosic a dition compounds to which my process is applicable. At the prescnt'time a colored nitrocellulose film base is the one that is most widel used and the specific details chosen for il ustralion will be directed to the treatment of it.

I dissolve the scrap or waste film base in a suitable solvent which, in the case of a nitrocellulose base, is preferably methyl alcohol or acetone or a mixture of these substances in any relative proportions. In order Application filed March 7, 1923. Serial No. 623,388:

to facilitate the solution of the scrap and in order to obtain an uncontaminated product,

'it is useful to chop up the scrap and wash it with hot water until the gelatinous coatings are removed. The amount of the solvent used for dissolving a given amount of scrap may be varied within wide limits, as

:alcohol-or acetone, or a mixture of them, re-.

lative to 1 part of film scrap to be a useful proportion. The scrap and so vent are conveniently charged into any of the well known dope mixers used in this art and agitated until a sufliciently homogeneous solution is obtained. This, of course, will be colored with the dye at this stage.

The solution is then broughtinto active Contact with decolorizing carbon, the inter action being sufficiently thorough to brin each ,part of the solution into contact wit some of the decolorizing material. can be most conveniently effected in thecase of the above described illustrative solution by passing it down through a verticalooluinn or mass of decol-orizin bone-char of the type used, for instance, in decolorizing sugar. Of course. other decolorizing forms of carbon may be emplo ed, such as proper 1' activated charcoal. lhe removal of the ye may take place completely b; main tainin the solution in contact with the boner for a sufiicient length of time say by proudin a long enough column 0% bone-char. Or it e dye may be removed step by ste such as by passing it repeatedly throng a mass of bone-char too small to extract the dye at the first contact. In this way a dope which is too'colored may be lessened in tint by a partial action of the carbon in. accordance with the principles of my invention.

The action takes place sufficiently rapidly to make it unnecessary to heat the materials above ordinary room temperature, although mild heating will, of course, assist the flowable qualities of the dope. When the car-.

Thisq met ods well known to those skilled in the I art. This restores the activity of i ma tei'ial and at the same time destroys the dye previously adsorbed or taken up by it. The

process has been found to operate success-' fully with a, large variety of both basic and acid dyes. I

Having thus described my invention, what I claim as new and desire to secure by Letters Patent iS:

1. The rocess of decolorizing a dyed cellulosic ad ition compound, which comprises dissolving said compound and treating the solution with decolorizing carbon.

2. The process of decplorizing a dyed cellulosic addition compound, which cornprises mixing said compound with sullioient solvein Lo form a flow-able solution and passing-said solution through derolorizinu bonechar, i

The process of decolorizing dyed nitrocellulose, which comprises bringin said nitrocellulose into solution and bringing said solution inio artirc contort with dcrolorizing carbon.

4. The process of decolorizing dyed nitrocellulose, whii-h COIIIPI'lSCSIHlXlHg said (0111- pound with sufiicicnl solvent to form a flowable solulion and passing said solution through dccolorizing bone-chm:

5. The proi-ess of decolorizing dyed nitroeellulose film h ;e, which comprises dissolv ing 1 purl then-of by weight in 12 parts by weight of rolntilc solvent and passing the solution through Lll(0lUllZlll f! rarhon.

6. The process of (lc-rolorizing dyed nitrocellulose lihn base. which (:oniprisrs (lissoliing it in :1 mixture containing wood alrohol until a 'fiownblesolnlion is obtained and liowin said solnlion lhrouslh u column oi D a A derolorizing bone-rlnu-.

Signed at Rochester, New York. this 20th day of February, v1923. EDlVARD b. FARRUW, .ln. 

